Telecontrol system



M. BERNARD 2,173,154

TELECONTROL SYSTEM Sept. 19, 1939.

Filed Nov. 1, 1935 Fig. '1

INVENTOR MARCEL BERNARD ATTO R N EY Patented Sept. 19 1939 TELECONTROL SYSTEM Marcel Bernard, Paris, France, ass'ignor to Compax e Generale Application} de Telegraphic Sans Fil, a corporation of France November 1, 1935 Serial No. 41,794 n France November 8, 1934 8 Claims. -(Ci. 178-31) This invention relates to a tele-control system and has particularly' to do with the use of signals for selective purposes where the signals themselves are characterized by their frequency components. The subject matter of this invention is related to that of French Patent No. 757,531 dated September 28, 1932, and comprises certain improvements thereover.

At the sending end, a signal is formed by the simultaneous transmission of two frequencies. If for instance, five frequencies A, B, C, D and E were available, it would be feasible to send out ten distinct signals each one thereof being composed of a selected pair out of five available frequencies, to wit: AB, BC, CD, DE, AC, BD, CE, AD, BE, and AE. Fundamentally speaking, the order of magnitude, that is, the particular frequencies may be chosen ad libitum, though in actual practice, for reasons of convenience both 20 in transmission as well as reception, the constituent" frequencies would be preferably of an acoustic or tonal value. For radio transmission these frequencies should be in the form of modulation frequencies imposed upon a carrier wave. Otherwise the mode of transmitting these frequencies and of separating the same, at the receiving end, from the carrier wave is well known and falls outside the scope of the present invention.

At the receiving end, the system comprises first a selector device for the different frequencies consisting of a set of resonant or tuned circuits. In the case here chosen by way of example, there are five such resonant circuits, each one'thereof being adjusted or tuned so that it will be responsive to one of the five component frequencies.

The system comprises further a relay system adapted to translate the components ofa signal into a selective control action. The number of relays in the system corresponds with the number of constituent frequencies. These relays are preferably of the thermionic tripping type, sometimes called Thyratrons. At any rate, they are of such a kind that the excitation or energization of the control electrode thereof will result in the flow of, or will release, a'. current from the local source without the mere cessation of the said energization causing the suppression or discontinuance of flow of'the currentcoming from the local source.

In a preferred embodiment of my invention I make use of relays in the output circuits of the aforementioned Thyratrons for combining the effects of the constituent frequencies of any 5 selected signal. These relays may be termed translating relays" since they have for their purpose to.close any one of a plurality of selective circuits, usually greater in number than the number of translating relays themselves. Each 60 selective circuit leads to an appropriate relay or other responsive device whereby the intended signal may be utilized. In circuit with the translating relays and the anodes of the Thyratrons I preferably employ a circuit breaker so that the control action of the Thyratrons may be discontinued when a signal ceases.

The details of construction of my invention and its mode of operation will best be understood upon reference to the following detailed. description when considered in view of the accompanying drawing in which 7 Figure 1 shows one embodiment illustratively and diagrammatically; and

Fig. 2 shows certain preferred refinements of .the circuits which are not shown in Fig. l merely because it would unduly complicate the circuits thereof.

Fig. 1 represents a schematic view of the selector deviceof the various component frequencies. The A. F. transformer I has its primary winding connected with terminals 2, that is, a wire transmission line or output end of a radio detector and receiver. The secondary of the transformer l is connected with resonant circuits 3A, 3B, 3C, 3D, 3E, each of which is appropriate to one of the constituent frequencies of the signals.

Each of the said circuits 3 comprises preferably an inductance and a. condenser connected in parallel, and is regulated and tuned so as to be responsive to one of the constituent frequencies AE. In series with each of the said circuits is connected a resistance r so that for a frequency having pulsation m of the corresponding resonant circuit there will obtain this relation:

' condenser, whereas the cathode is associated with the other terminal of the condenser with the interposition in the connection of a polarizing or biasing source 5 and a bias resistor 8, if desired.

The output circuit of each Thyratron 4A, 43, etc., includes a translating relay 1A, 13, etc., and a common return circuit which includes a circuit breaking relay F. It will be seen from this arrangement that the Thyratrons, although they may be tripped by a signal, are immediately deenergized upon becoming conductive since the circuit breaking relay F becomes energized, attracts its armature away from the back contact Each, therefore, includes a pair of contacts P thereof and interrupts the circuit which included actuated by one relay and a pair of contacts N actuated by another relay. Between the P contacts and the N contacts are the windings 9 'of the relays Q'to' Z inclusive. Each armature of the P contacts connects with the positive pole of the battery 5. Each armature of the N contacts connects correspondingly with the negative pole of the battery 6.

In order to illustrate the selective action of any two translating relays working in combination it may be assumed that the combination of frequencies in a given signal is such as to actuate the Thyratrons 4A and 4C simultaneously. Relays IA and 10 will likewise be actuated. In this case a circuit is closed from the positive side of the battery 6 through the P contacts of relay 1A to the winding 9 of relay R and thence to the left hand armature N of relay 10 which connects to a common return circuit to the negative side to the battery 6. The selective circuits for actuating any one of the relays Q to Z inclusive may likewise be traced.

It is frequently desirable that means should be provided for locking any one of the relays Q to Y inclusive in an energized position. For carrying out this object I have shown each relay as having a locking winding ID in circuit with a front contact l2 cooperating with the armature of the relay so as to feed current from the battery 6 directly to the winding I 0 and thence through the contact l2, circuit breaking contacts ll of the relay Z and from there back to the negative side of the battery 6. In accordance with this arrangement it will be seen that any one of nine signals may be used to select and energize the relays Q toY inclusive whereas a signal composed of frequencies such as to actuate I'hyratrons 4C and IE will in combination select the relay Z for opening the locking circuit in whatever one of the relays Q to Y that was'energized.

It will be understood by those skilled in the art that I am not limited in the carrying out of my invention to a system in which only five Thyratrons and their associated translating relays would be used and whereby only ten selections would be obtainable, but that the number of 'I'hyratrons may be as many as desired while the relay arrangements may be such as to obtain a selective action in response to code signals having more than two frequency components. In fact it may readily be seen that the system is adapted for use in well known printing telegraph systems such as those operable by five-unit code signals, where marking impulses are represented by' the transmission of different frequencies characterizing the first to the fifth unit of the code, and the spacing signals are represented by the absence of transmission of such frequencies.

It may be pointed out here that as one of the modifications of the system falling inside the spirit and the scope of this invention it would be feasible to use numerous permutations of simultaneously transmitted frequencies, that is to say,

each signal could be characterized by and be formed of more than just two frequencies. It is well known that the 5-unit code provides the possibility for selecting any one of 31 different effects in response to the 31 possible permutations of different elements of a 5-unit code signal,

where a complete blank, that is, no signal in each of the 5 units, is not considered. If. a complete blank were to be considered then any one of 32 selections might be made. U. S. Patent #1,786,805 to Wensley, for example, shows how any one of 31 selections may be made by the simultaneous actuation of five relays or less in response to simultaneously received signal elements each identified by a different frequency, and each selection being the result of a different permutation of said elements. My invention, however, differs from the disclosure of said Wensley patent primarily in respect to the combination of parts comprised in the frequency responsive means in combination with any desired relay system the choice of which would depend largely upon the use to be made of the selective system. Such a selective system may, of course, be used in various ways as, for example, for the remote control of different kinds of apparatus as in radio distress call signalling or in devices for steering a craft. Where the signalling system provides for the simultaneous transmission of as many as five different frequencies, however, it is equally possible to utilize my system for controlling a printing telegraph receiver, as will be found mentioned hereinafter.

The circuit diagram of Fig. 1 was made as simple as possible in order to illustrate the principles of selection by means of code signals each having two frequency components. The circuit diagram may be understood, however, to be further amplified with refinements of structure so as to insure greater dependability and freedom from stray signals and impulses. Indeed, when the component frequencies are distributed over the acoustic or telephonic (tonal) frequency spectrum-and this, as has been pointed out before, is of practical advantagethen, in thelight of practical experience, it may happen that the receiver is acted upon by a stray telephone or musical transmission.

Now, in order to obviate such serious difiiculty and. occurrence, the invention provides an im- 1 proved type of arrangement as shown in Fig. 2 designed to be connected between the resonant circuit 3 and the grid 13 of the corresponding Thyratron. According to this arrangement the grid l3 instead of being energized as in Fig. 1 by the alternating voltage prevailing across the terminals of the resonant circuit 3 is excited by the direct current voltage set up across the terminals of an auxiliary condenser I obtained by virtue of rectification of the preceding alternating voltage in a rectifier I 5. This may be either a euprous-oxide rectifier, a thermionic valve, or equivalent means, and should preferably be disposed in series with aresistance I 6 to preserve the over-voltage of the resonant circuits, with the current flowing in the direction indicated by the arrows.

The energization of the Thyratron is thus subordinated to the length of excitation of the resonant circuit which may be readily rendered longer than the occasional energization due' to a telephonic stray or jamming effect. However, as soon as the Thyratron has been energized, a grid current of ionic origin will arise, and this would tend to keep the condenser l4 charged.

In order to compensate for, or prevent the existence of, this currentwithout interfering with the flow'of the normal current, a uni-directionalor valve-type conductor or rectifier l1 suitably directed is interposed between the condenser l4 and the grid l3. Moreover, a resistance l8 which is in'series relation to the grid l3 assists in uncoupling the Thyratrons in relation to. one another. a 0n the other hand, a resistance l9 across the terminals of the condenser l4 insures the discharging of this condenser at the end of an interval of time which is a function of the constants of the circuit after cessation of the signal. In order to abbreviate this time a contact 20 short-circuits the condenser H, the relay controlling this contact .operating simultaneously with, though preferably with a slight time lag in reference to, the control relays affected by the Thyratron in question. The resistance 19, however, is necessary for insuring discharge subsequent to a charging effect due to a stray or jamming signal which has failed to operate the control relay.

It is also useful to introduce in the arrangement means adapted to secure protection from disturbance which, though brief, may at 'the same time be very powerful (atmospheric strays, for instance); and thus capable of sufliciently charging the condenser 14. With this end in view, there is connected across the terminals of the secondary of the input transformer means to produce a limiter action consisting of a valve or dry rectifier and constituted in the following fashion: a potentiometer resistance 2| is disposed across the terminals of a direct current source of potential, for which object there could be used the plate potential source of the Thyratrons. ed with one of the terminals of the secondary of transformer l by means of a rectifier 22. One of the ends of the resistance 2! is united with the other respective terminal of the secondary of transformer I by way of a polarizing or biasing source 5, while a condenser 23 is used to bridge the slider contact.

In the operation of my invention it can be seen from the foregoing description that there area number of advantages to be obtained over the use of devices 'heretoforeknown in the art. The invention has particular utility in systems where it is desired to obtain any one of a'number of different selections of apparatus to be .remotely I controlled. The choice of two" modulating frequencies to be applied to a carrierwave for making a selection is in compared with the employment of a greater number of frequencies simultaneously" superposed upon a carrier wave. However, as hasbeen previously pointed out, it is within the scope of the invention to utilize code signals composed of signaling elements of any number, say, for example, five, corresponding with the well known fiveunit code systems as used in teletypewriter oper ,ation. The system may also be used for making selection of a receiving station to be actuated by a given transmitter when a called station has been caused to respond to its appropriate signal. The responsive device at that station can be caused automatically to put its receiving apparatus in condition to receive a message. The receiving station when so conditioned may be maintained in that state by use of the locking circuits heretofore described, and subsequently disconnected by the sending .of a signal to actuate, the relay Z. This and other methods of starting and The slide of the potentiometer is connectthe interest of'csimplicity as each constituting a responsive unit correspondingto one of a plurality of selective units of a code signal, a corresponding plurality of thresholdtype electron discharge tubes each having an input circuit, means including a capacitor-resistor combination having a predetermined time constant for delaying the response of said discharge tubes to incoming signals, said means being severally interposed each in circuit between one of said resonant networks and an appropriate input circuit for one of said electron discharge tubes, and means for accelerating the discharge rate of the capacitor in the first said means in relation to the charging rate.

2. Receiving apparatus in accordance with claim 1 and having rectifying means-for building up a cumulative charge on said capacitor.

3. Receiving apparatus in accordance with claim 1 and having means for dissipating stray interference impulses of shorter duration than the signaling impulses to which said electron discharge tubes are to be rendered responsive.

4. Receiving apparatus 4 in accordance with claim 1 and having means for adjusting the critical value of the reactances in accordance with a desired condition of threshold response of said electron discharge tubes.

5. Receiving apparatus in accordance with claim 1 and having a relay responsive to a signal for actuating the discharge accelerating means.

6. Telegraph receiving apparatus comprising a resonant network tuned to and adapted to receive signals 'of a given frequency, a threshold-type electron discharge tube having input and output circuits, a time delay circuit constituted by a resistor and a capacitor suitably connected between said resonant network and said input circuit for rendering said discharge tube responsive to (lot impulses of an operating threshold value not in said input circuits and of at least a predetermined duration, and

means for accelerating the discharge rate of said capacitor inrelation to its charging rate.

'7. Apparatus in accordance with claim 5 and having relay means in the output circuit of said connection between said tuned network and the input side of said dischargetube, means including a capacitor shunted by a resistor for delaying the response to signalling impulses in said discharge tube, and means operative from the output side of said discharge tube for hastening the recovery ofsaid apparatus to a normal-no-signal condition when each of said signalling impulses is terminated.

MARCEL BERNARD.

discharge tube operative to control the acceleration of the discharge rate .in said capacitor and receiving apparatus comcharge tube, auni-directional resistive circuit 3 

